Bis-pyrrolidone-formaldehyde addition products and their use as crosslinking agents with cellulose

ABSTRACT

A NEW ALKYLENE BIS-PYRROLIDONE-FORMALDEHYDE ADDITION PRODUCT WASS PREPARED BY THE BASE CATALYZED ADDITION OF EHTYLIDENEBIS-3-(2-PYRROLIDONE) TO FORMALDEHYDE IN MOLE RATIOS OF ABOUT FROM 1:1 TO 1:3 IN AQUEOUS SOLVENT. THE NEUTRALIZED SOLUTIONS PREPARED OF THE NEW CHEMICAL COMPOUND WERE USED EFFECTIVELY TO CROSSLINK COTTON FABRICS EMPLOYING A PAD-DRY-CURE PROCEDURE. THE RESULTANT FABRICS WERE FOUND TO BE WRINKLE RESISTANT AND TO HAVE RESISTANCE TO CHLORINE DAMAGE, AND THE CROSSLINKS WERE RESISTANT TO ACID AND BASIC HYDROLYSIS.

United States Patent 3,567,361 BIS-PYRROLIDONE-FORMALDEHYDE ADDITION PRODUCTS AND THEIR USE AS CROSSLINKING AGENTS WITH CELLULOSE Sidney L. Vail, New Orleans, La., assignor to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Aug. 29, 1969, Ser. No. 854,292 Int. Cl. (10711 27/08; D06m 13/14, 13/38 US. Cl. 8-1163 4 Claims ABSTRACT OF THE DISCLOSURE A new alkylene bis-pyrrolidone-formaldehyde addition product was prepared by the base catalyzed addition of ethylidenebis-3-(2-pyrrolidone) to formaldehyde in mole ratios of about from 1:1 to 1:3 in aqueous solvent. The neutralized solutions prepared of the new chemical compound were used effectively to crosslink cotton fabrics employing a pad-dry-cure procedure. The resultant fabrics were found to be wrinkle resistant and to have resistance to chlorine damage, and the crosslinks were resistant to acid and basic hydrolysis.

A non-exclusive, irrevocable, royalty-free license in the invention herein described throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the treatment of cellulosic textile materials to produce textiles having improved physical and chemical properties. Specifically, this invention relates to new textile treating agents and to the process for treating cotton or other cellulosic fabrics with these new chemical compounds hereby imparting to these fabrics wrinkle resistance and durable-press properties. More specifically, the present invention relates to the production of N,N'-dimethylol derivatives of ethylidenebis-(Z-pyrrolidones) which are useful in imparting increased resilience to cotton and other cellulosic fabrics.

In general, the production of wrinkle resistant and durable-press fabrics has been accomplished by the use of diand polyfunctional N-methylol finishing agents. These agents are generally formed by the addition of formaldehyde to ureas (cyclic or straight chain), melamine, and other similar type compounds. However, it is well known that the finish, i.e. crosslinks, produced from these agents are fairly easily broken or removed by repeated washing procedures which employ moderately strong acidic solution, that is, the souring step used in most commercial launderings. After such treatments, it is often found that the treated fabric has lost the finish and the desired wrinkle resistance and durable-press properties. Consequently, these treating agents cannot be used to produce acceptable durable-press cellulosic fabrics which are to be subjected to these, or similar, hydrolytic conditions.

N,N-dimethylol alkyl carbamates have been widely used in the industry to produce finishes for durable-press and wash-and-wear finishes with acceptable resistance to acidic hydrolysis. However, these formulations from alkyl carbamates and formaldehyde are known to contain much uncombined formaldehyde. This formaldehyde is partially released in the finishing plant, but much of it is released continually during further processing. The total amount of formaldehyde released in this manner is considered to be unacceptable for many uses. For example, in delayedcuring procedures the agent is padded onto fabric and the fabric is dried. The dry fabric is usually stored and cured at some latter date, possibly after being made up into a garment. During this period it is most important "ice that only a minimum amount of formaldehyde be released.

The primary object of the instant invention is to describe a new crosslinking agent which can be used in conventional or in delayed-curing procedures in the textile industry with little or no formaldehyde odor released from the finished product.

A secondary object of the instant invention is to provide the process of the primary object with the added qualities of resistance of the finish to both acid and alkali hydrolysis to a degree which is comparable to those finishes in the trade which are reputed to have high resistance to acidic hydrolysis.

These and other objects of the instant invention are accomplished by treating the cellulosic textile with an aqueous solution containing the N-methylol derivatives of bispyrrolidones having the general structure wherein A is an alkylene or substituted alkylene bridge of 1 to 4 carbon atoms joining two N-methylolpyrrolidone groups at the 3, 4, or 5 positions. A particularly effective compound of this type is the N,N'-dimethylol derivative of ethylidene-bis-3-(2-pyrrolidone), which has the structure The N-methylol derivatives of the bispyrrolidones used for the treatment of the cellulosic textile in the process of this invention can be conveniently obtained by the reaction of formaldehyde with the bispyrrolidone (prepared according to the process of US. Pat. 3,252,995) in aqueous media under slightly alkaline conditions. It is preferred to employ about one molar equivalent of formaldehyde for each pyrrolidone group. Formaldehyde in ex cess of one molar equivalent leads to a subsequent release of the excess formaldehyde. On the other hand, a lower amount of formaldehyde reduces the crosslinking ability of the agent and can result in lowered resillience of the fabric.

The temperature of the methylolation reaction can be varied to control the rapidity of reaction; however, the preferred temperatures are about from 20 to C., using a longer reaction time with the lower temperature. For example, a reaction time of about /2 hour at 60 C. is usually adequate, whereas overnight reaction at room temperature is commonly employed.

Following completion of the methylolation procedure the aqueous solution containing the reaction product is made slightly acidic and is diluted to about the desired concentration for treatment of the cellulosic material. An acidic substance, or substance producing acidity at elevated temperatures, is added to the solution to serve as catalyst. The concentration of the reaction product in the dilute solution can be varied depending on the particular textile processing conditions used, the type of textile being treated, and the properties desired in the finished textile. It is generally preferred to use about 3% to 20% by weight of the reaction product in the dilute treating solution. A metal salt of a, strong mineral acid is a suitable acidic catalyst to add to the treating solution of the process of the present invention. Magnesium chloride and zinc nitrate are examples of particularly suitable catalysts, and concentrations of about from 0.2% to 3.0%, by weight, of the acidic catalyst are generally preferred.

Treatment of the cellulosic textile fabric according to the process of the instant invention comprises uniformly impregnating (thoroughly wetting) the textile with the above-described treating solution, mechanically removing excess liquid, then drying and curing the goods. These steps can be conveniently carried out with conventional textile finishing equipment. The wet pickup (increase in weight of the textile upon wetting), after mechanically removing excess liquid, should preferably be about 60% to 80% when using the preferred treating solution. Adjustment to the desired wet pickup can be conveniently achieved by passing the impregnated textile through squeeze rolls or the like. The drying time and temperature are not critical, but it is preferable to dry the wet textile at relatively low temperatures, that is, about from 60 to 100 C., until the textile is dry to the touch. The textile may be stored at this point. The textile is cured by subjecting it to a higher temperature, about from 130 to 180 C., for periods of time ranging about from /2 minute to 15 minutes, to cause reaction of the applied materials. In the curing operation, the longer time is used with the lower curing temperatures.

Following the curing operation it is preferable-but not necessaryto water-wash the treated textile to remove any unreacted materials. The washing operation can be carried out using the procedures and equipment conventionally employed for the washing of textiles. After it is washed and dried, the treated textile has the same appearance as the original untreated textile, and its feel is also essentially unchanged; but the treated fabric possesses resiliency, wrinkle resistance, and the other desirable properties previously described.

In addition to being employed as the sole methylol agent in the treating solution of the present invention, the N-methylol derivatives of this invention may also be used in combination with various conventional treating agents to produce economical and improved cellulosic textile products. Softeners and other additives may be used if desired.

The process of the instant invention can be used to treat substantially any hydrophilic fibrous cellulosic material such as cotton, rayon, ramie, jute, and the like, which can be impregnated with a liquid, dried, and then cured.

The following examples are provided by way of illustration of how the invention can be reduced to practice, and these are in no way meant to indicate limitation of the invention. The detailed procedures given below in the examples are illustrative, and are not the only nor the specific conditions for the production of an acceptable finished textile. Modification of these procedures can be made, as will be apparent to those skilled in the art. In the examples all parts and percentages are by weight, unless noted otherwise. The treated cellulosic fabrics were tested by these methods. Wrinkle Recovery by the ASTM (Monsanto Method) D1295-60T; and Breaking Strength by the ASTM Method Dl682-59T; Retained Chlorine Damage by the AATCC Method 92-1962 Scorch Test standard method.

SUMMARY OF THE INVENTION In summary, the instant invention can best be described as (1) an alkylene bispyrrolidone-formaldehyde addition product of the general formula CsH C H c M4 3 aye; ool s HzOH CHzOH wherein A is an alkylene or substituted allylene bridge of 1 to 4 carbon atoms joining two N-methylolpyrrolidone groups at the 3, 4, or 5 positions, and (2) a process for imparting to cotton and other cellulosic fabrics the qualities of wrinkle resistance, and resitance to chlorine damage, and the finish produced possesses resistance to acid and alkali hydrolysis, by reacting the cotton and other cellulosic fabric with the bispyrrolidone-formaldehyde ad dition product described above.

4 EXAMPLE 1 The bispyrrolidone-formaldehyde addition products were prepared as follows: A 1.2 and a 2.5 molar equivalent of formaldehyde (as a Formalin solution) were added to ethylidenebis-3-(Z-pyrrolidone) and water (five times the weight of the bispyrrolidone). The mixtures were adjusted to a pH of 10, stirred, and allowed to stand overnight. The solutions were then adjusted to pH 5 to 6 with dilute hydrochloric acid. A catalyst was added and the solutions were diluted with water to the desired concentrations, which were about 10% of the agent, expressed as percent unmethylolated ethylidenebis-3-(2-pyrrolidone) and 0.7% catalyst, expressed as percent zinc nitrate hexahydrate.

EXAMPLE 2 Fabric treatments: Samples of x 80 cotton printcloth were dipped in the solutions of Example 1 and padded to give about 70% increase in weight of the fabric. The wet impregnated fabrics were dried 7 minutes at 60 C. The sample padded in the solution containing 1.2 molar equivalent of added formaldehyde was cured immediately for three minutes at 160 C. Fabric samples padded in the solution containing 2.5 molar equivalent of added formaldehyde were given (after drying) an immediate and a delayed cure. Thus, one of these fabric samples was cured immediately for 3 minutes at 160 C. The second fabric sample was stored in a plastic bag for a month and then cured for 3 minutes at 160 C. All samples were washed in a warm alkaline water solution containing a nonionic detergent, and tumble dried. Selective testing was performed on these three samples. This data is presented in Table I for comparative evaluation.

TABLE I.-FABRIC TREATMENT Ratio, HCHO to bispyrrolidone Wrinkle recovery angles Add-0n (percent) Warp, Filling,

NOTE: No softener was used in any of these samples. Sample 3 was stored for one month, then cured. The ratio number of column 2 has reference to the ratio of formaldehyde to bispyrrolidone in molar equivalents.

EXAMPLE 3 The fabric samples from Example 2 were tested for the durability of the finish: (A) for resistance of the finish to acid hydrolysis, (B) for resistance of the finish to hydrolysis during conventional home laundering, and (C) for scorch damage from hypochlorite bleach.

An aqueous stripping solution of 1.5% phosphoric acid and 5% urea at 80 C. for 30 minutes is often used to remove conventional urea-based finishes from cotton. Fabric samples 1 and 2 (see Table I) were submitted to this stripping treatment and were found to contain 36% and 51%, respectively, of the nitrogen content of the original treated fabric. These stripping conditions are strong enough to remove all but about 5% of the nitrogen from fabrics treated with urea-formaldehyde formulations or with dimethylolethyleneurea. Fabrics with an acid resistant finish such as dimethylol ethyl carbamate generally retain 30 40% of the original nitrogen content after stripping under these conditions.

Sample 3 was subjected to 30 alkaline home laundering cycles. The wrinkle recovery angle of 274 (Warp plus Filling) of the original treated fabric was decreased to only 257 (Warp plus Filling) by the thirty washing cycles.

In the Scorch Test (for chlorine damage) fabrics treated with the bispyrrolidone were found to have little or no susceptibility to chlorine damage. These data are shown in Table II.

TABLE II.SCORGH TEST RESULTS Scorch test,

Breaking strength strength retained Sample Number (pounds) (percent) 1 40 98 2 34 100 Untreated cotton -100 We claim:

1. A process of modifying a cellulosic fabric which comprises treating said fabric with an aqueous solution containing an acidic catalyst and 3% to Weight of a bispyrrolidone-formaldehyde addition product of the formula I 6 of N,N'-bis(hydroxymethyl)ethylidenebis 3 (2- pyrrolidone) and about from 0.2% to 3.0% by weight of an acid type catalyst selected from the group consisting of magnesium chloride and zinc nitrate,

5 (b) drying the wet impregnated fabric at about from to C. until the textile is dry to the touch, and

(c) curing the dry impregnated fabric at about from 10 to C. for periods of time ranging about from 0.5 to 15.0 minutes. 3. The process of claim 2 wherein the acid type catalyst is magnesium chloride.

4. The process of claim 2 wherein the acid type cata- 15 lyst is zinc nitrate.

References Cited UNITED STATES PATENTS 3,252,995 5/1966 Grosser et a1. 260-3263 3,486,838 12/1969 Randall et al 8-1163 FOREIGN PATENTS 1,070,588 12/1959 Germany 8116.3

25 GEORGE F. LESMES, Primary Examiner I. CANNON, Assistant Examiner US. Cl. X.R. 

